SCIENCE SEMINAR
IN SEARCH OF THE DARK SIDE
OF THE UNIVERSE AND OTHER COSMIC PUZZLES
Prof. Peter K.S. Dunsby
Dept. of Mathematics & Applied Mathematics
University of Cape Town, South Africa
Friday, January 25, 2008
12:30 p.m.
Bishop Williams Hall
Abstract: Over the past decade there has been considerable progress in our understanding of the universe, largely due to the impact technological advances have had on observational cosmology. The detailed understanding of cosmic microwave background anisotropies and the formation of large-scale structure, together with type Ia supernova measurements have allowed cosmologists to constrain the basic parameters of the universe to such an extent, that we now have a model that appears to fit almost all available data - the so called "concordance model". My talk will trace the history of the standard cosmology by explaining how we measure the terms that make up the famous Friedmann equation - also know as "The Cosmic Triangle" - that describes the evolution of the universe according to the General theory of Relativity.
The Cosmic Triangle eliminates a number of popular models, such as a high-density universe that is slowing down and will eventually re-collapse, as well as a nearly empty universe with no dark energy and low mass. While the evidence from galactic clusters shows that mass density is low, the type Ia supernova evidence for acceleration shows that dark energy must dominate the density today. This is a description of the universe we would never have predicted 20 years ago and might require new physics to explain what we observe. It is just possible that these measurements might be pointing towards a break down of Einstein's famous theory on cosmological scales - an exciting prospect!
